Immune dysfunction as a risk factor for long-term mortality from staph infections

Each year more than 650,000 U.S. patients are affected by severe sepsis, a process by which an infection leads to deregulated inflammation throughout the entire body. About 20 percent of these patients – more than 120,000 – die in the hospital.

Among those who survive the initial hospitalization, about 25 percent die within the following year.

UChicago’s Institute for Translational Medicine awarded Jared Greenberg, MD, a University of Chicago Medicine Fellow in the Section of Pulmonary and Critical Care Medicine, one of its Pilot Awards to investigate the types of patients who are at the highest risk for long-term mortality after sepsis.

“We’re trying to figure out why people who survive a severe infection have a higher mortality than their counterparts,” Greenberg said. “While there are algorithms to treat sepsis in the first 24 hours, there is really no way to identify people who are going to have complications afterward.”

Greenberg chose to focus on Staphylococcus aureus bacteremia because it is a common infection that typically causes a systemic inflammatory response. He initially reviewed 237 patients with Staphylococcus aureus bacteremia at the University of Chicago medical center and found that clinical immunosuppression prior to infection was a risk factor for 31- to 90-day mortality, but not 30-day mortality. He is now using the ITM Pilot award to measure immune markers among a group of prospectively enrolled patients with Staphylococcus aureus bacteremia.

“I’m hoping to be able to use clinical and biochemical factors to risk stratify patients who survive an infectious process,” Greenberg said. “Clinicians could use this information to have heightened vigilance for clinical changes among patients with a high risk for poor outcomes.

Additionally, clinical trials for patients with sepsis may have greater chance of success if they only enroll high-risk patients.”

Jared Greenberg, MD

Greenberg became interested in the immunosuppressed population during his residency at Emory University in Atlanta, a region where there was a large population of people infected with HIV.

“I found it really interesting that when patients with HIV would come to the Intensive Care Unit, they would often be sick with infections associated with prolonged healthcare exposure instead of unusual, opportunistic infections,” he said.

Greenberg was the first author on a paper highlighting his Staphylococcus aureus bacteremia findings that was published in February 2014 by PLoS One. He said he returned to clinical work in July and plans to work on a K23 grant application.

“It’s going to be very important when I apply for my K Award to have this preliminary data,” Greenberg said. “Without the ITM Pilot Award money, it would be difficult to do this initial research.”